Moving Body Cooling Apparatus

ABSTRACT

To obtain a moving body cooling apparatus which can improve cooling performance through efficient use of traveling wind produced as a moving body is running. The direction of grooves  4   f  formed by flat-shaped cooling fins  4   c  provided integrally with a base portion  4   a  to which semiconductor devices to be cooled are affixed is inclined from a moving direction of a car body  1  which is an example of a moving body. As the car body  1  runs, traveling wind passes through the grooves  4   f  as shown by an arrow C. As the length of the grooves  4   f  becomes shorter, pressure loss due to passage of the wind decreases, flow rate of the wind increases, and the amount of heat to be removed from the flat-shaped cooling fins  4   c  on both sides of each groove  4   f  decreases. Therefore, temperature increase in the traveling wind is reduced and cooling performance is improved.

TECHNICAL FIELD

The present invention relates to a moving body cooling apparatus for cooling a heat-generating element like a semiconductor device mounted on a moving body, such as a railroad car. More particularly, the invention pertains to a moving body cooling apparatus which utilizes relative wind (traveling wind) produced as a moving body is running.

BACKGROUND ART

A conventional moving body cooling apparatus for cooling a heat-generating element like a semiconductor device mounted on a moving body, such as a railroad car, is configured such that cooling fins for dissipating heat generated by the semiconductor device are arranged parallel to a moving direction of the car (refer to Patent Document 1, for example).

Patent Document 1: Japanese Laid-open Patent Application No. 2003-258471 (paragraph 0025 and FIG. 1)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The aforementioned conventional moving body cooling apparatus has had a problem that it has been impossible to obtain a sufficient amount of airflow from the traveling wind flowing between the cooling fins due to pressure loss caused by friction with the flat-shaped fins, for example, resulting in a reduction in cooling performance. There has also been a problem that the temperature of the traveling wind would increase as a result of heat exchange performed on an upstream side, thereby causing a reduction in cooling ability of the flat-shaped fins on a downstream side. There is a possibility that a temperature-sensitive protective device for a downstream-side semiconductor device trips if the cooling ability of the flat-shaped fins on the downstream side drops. To prevent tripping of the temperature-sensitive protective device, it would be necessary to increase the surface area of the cooling fins, and thus the volumetric capacity of a cooling unit, to increase thermal capacity thereof for achieving a satisfactory cooling ability. This approach has had such problems as an increase in weight, increase in cost, and so on.

The present invention has been made to overcome the aforementioned problems. Accordingly, it is an object of the invention to provide a moving body cooling apparatus which can improve cooling performance through efficient use of traveling wind produced as a moving body is running.

Means for Solving the Problems

A moving body cooling apparatus according to the present invention is intended to be installed on a moving body, the moving body cooling apparatus including a heat sink which is provided with a heat-generating element mounting portion on which a heat-generating element to be cooled is mounted, and a cooling fin block formed integrally with the heat-generating element mounting portion, the cooling fin block having a plurality of cooling fins which form grooves extending in a direction inclined from a moving direction of the moving body.

ADVANTAGEOUS EFFECTS OF THE INVENTION

The moving body cooling apparatus of the present invention is intended to be installed on a moving body. Since the moving body cooling apparatus includes a heat sink which is provided with a heat-generating element mounting portion on which a heat-generating element to be cooled is mounted, and a cooling fin block formed integrally with the heat-generating element mounting portion, the cooling fin block having a plurality of cooling fins which form grooves extending in a direction inclined from a moving direction of the moving body, the length of the grooves becomes shorter, pressure loss due to passage of wind decreases, and flow rate of the wind increases. Also, the amount of heat to be removed from the flat-shaped fins on both sides of each groove decreases. Therefore, temperature increase in traveling wind is reduced and cooling performance is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram showing an on-board cooling apparatus.

FIG. 2 is a structural diagram showing the detailed structure of a heat sink of the on-board cooling apparatus.

FIG. 3 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a second embodiment of the present invention.

FIG. 4 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a third embodiment of the present invention.

FIG. 5 is a structural diagram showing a heat sink unit of an on-board cooling apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a structural diagram showing a heat sink unit of an on-board cooling apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a sixth embodiment of the present invention.

FIG. 8 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a seventh embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION First Embodiment

FIGS. 1 and 2 show a first embodiment for carrying out the present invention, in which FIG. 1 is an explanatory diagram showing an on-board cooling apparatus serving as a moving body cooling apparatus mounted on a vehicle, and FIG. 2 is a structural diagram showing the detailed structure of a heat sink of the on-board cooling apparatus. As shown in FIG. 1, an electrical equipment box 2 is mounted on the bottom of a floor of a railroad car body 1 which is an example of a moving body provided with a door 1 a by means of mounting metal parts 100. The heat sink 4 is affixed to a side surface of the electrical equipment box 2. Also mounted on the floor bottom of the car body 1 is another electrical equipment box 7.

The heat sink 4 has a flat-shaped base portion 4 a and a cooling fin block 4 b which is formed integrally with the base portion 4 a. The cooling fin block 4 b is configured with parallel, flat-shaped cooling fins 4 c which are arranged to make a specific angle θ (FIG. 2) with a moving direction A of the car body 1, the flat-shaped cooling fins 4 c forming grooves 4 f through which traveling wind that is an airflow produced as a result of movement of the car body 1 flows (as will be discussed later in detail). In this embodiment, four semiconductor devices 5, which are heat sources that generate heat to be dissipated, are firmly fixed to the base portion 4 a. In this structure, the grooves 4 f formed by the flat-shaped cooling fins 4 c are arranged in such a manner that the grooves 4 f run in a direction B forming an oblique angle of θ (30° in this example) with respect to the moving direction A of the car body 1.

As the direction of the grooves 4 f formed by the flat-shaped cooling fins 4 c is inclined with respect to the moving direction A of the car body 1 in the aforementioned fashion, the traveling wind flowing into the grooves 4 f passes through the grooves 4 f as shown by an arrow C in FIG. 2. Heat generated by the semiconductor devices 5 is conducted from the base portion 4 a of the heat sink 4 to the flat-shaped cooling fins 4 c and a heat exchange process is performed between the flat-shaped cooling fins 4 c and the traveling wind which has flowed into the grooves 4 f formed between the flat-shaped cooling fins 4 c. Consequently, the semiconductor devices 5 are cooled as the heat is dissipated. It is to be noted that upstream and downstream sides are reversed when the car body 1 moves in a reverse direction.

As the flat-shaped cooling fins 4 c are so arranged that the direction B of the flat-shaped cooling fins 4 c is oblique to the moving direction A of the car body 1, the length of the grooves 4 f becomes shorter and pressure loss decreases. As a consequence, flow rate of the traveling wind (cooling wind) passing through the grooves 4 f increases and the fresh traveling wind flowing along side surfaces of the flat-shaped cooling fins 4 c can be taken in down to the downstream side of the heat sink 4, making it possible to improve cooling performance. Additionally, this structure helps to alleviate the problem concerning the reduction in cooling ability on the downstream side of a conventional heat sink due to a temperature increase in the traveling wind occurring as a result of heat exchange between the flat-shaped cooling fins 4 c and the traveling wind on the upstream side. It is therefore possible to improve the cooling performance and achieve a reduction in size and weight of the heat sink.

While, in the foregoing discussion and FIGS. 1 and 2, the grooves 4 f formed by the flat-shaped cooling fins 4 c have been illustrated as being arranged parallel to a direction from an upper-left side of the electrical equipment box 2 to a lower-right side thereof, in which the traveling wind flows, orientation of the grooves 4 f is not limited to this direction. For example, the grooves 4 f may be oriented along a direction from a lower-left side of the electrical equipment box 2 to an upper-right side thereof, and the angle θ formed between the moving direction A of the car body 1 and the grooves 4 f may be determined as appropriate. Furthermore, the base portion 4 a and the cooling fin block 4 b need not be formed as a single piece. Instead, the base portion 4 a and the cooling fin block 4 b may be separately manufactured and firmly joined together so that a specific level of thermal conductivity is obtained between both.

Second Embodiment

FIG. 3 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a second embodiment of the present invention. The heat sink shown in FIG. 3 is affixed to the side surface of the electrical equipment box 2 shown in FIG. 1 in the same way as the heat sink 4 of the first embodiment. As shown in FIG. 3, the heat sink 14 has a base portion 4 a and four cooling fin blocks 14 b placed on the base portion 4 a with specific spacings between the individual cooling fin blocks 14 b. This heat sink 14 is shaped as if the cooling fin block 4 b of FIG. 2 is divided into the four cooling fin blocks 14 b by providing cross-shaped slots 4 d, 4 e running in directions parallel to and perpendicular to the moving direction of the moving body 1 for passing the traveling wind. An average length of flat-shaped cooling fins 14 c is 45% that of the flat-shaped cooling fins 4 c, the distance between the individual flat-shaped cooling fins 14 c is the same as that between the flat-shaped cooling fins 4 c, and the width of grooves 14 f is the same as that of the grooves 4 f in the heat sink 4 of FIG. 2.

While a total surface area of the flat-shaped cooling fins 14 c of the four cooling fin blocks 14 b is approximately 81% that of the flat-shaped cooling fins 4 c of FIG. 2, it is possible to achieve almost the same level of cooling performance. This will be discussed later in detail. Four semiconductor devices 5 are firmly affixed to the base portion 4 a on an opposite side of the cooling fin blocks 14 b with centers of the four semiconductor devices 5 matched with centers of the individual cooling fin blocks 14 b. The heat sink 14 of this kind is manufactured by precision casting of an aluminum alloy, for example.

Next, the working is described. Heat generated by the semiconductor devices 5 is conducted from the base portion 4 a of the heat sink 14 to the flat-shaped cooling fins 14 c which are formed integrally with the base portion 4 a and a heat exchange process is performed between the flat-shaped cooling fins 14 c and the traveling wind which has flowed into the grooves 14 f, so that the semiconductor devices 5 are cooled. If the heat sink 14 is shaped as if the cooling fin block 4 b of FIG. 2 is divided into the four cooling fin blocks 14 b with the provision of the slots 4 d, 4 e which permit passage of the traveling wind in the aforementioned fashion, the average length of the grooves 14 f becomes 45% that of the grooves 4 f. Consequently, pressure loss occurring when the traveling wind passes through the grooves 14 f decreases and flow rate of the traveling wind increases, resulting in an eventual improvement in cooling efficiency. The cooling fin blocks 14 b are shaped as if divided into two (upper and lower) parts (four parts in total) by the slot 4 d which is parallel to the moving direction of the car body 1, or an inflow direction of the traveling wind. Accordingly, if the same amount of heat is to be deprived of by the cooling fin blocks 14 b as by the cooling fin block 4 b of FIG. 2, the temperature increase in the traveling wind would be halved at outlets of the grooves 14 f. It is therefore possible to perform an efficient heat exchange even on the downstream side of the flat-shaped cooling fins 14 c. This structure ensures the same level of cooling performance as achieved with the flat-shaped cooling fins 4 c even though the flat-shaped cooling fins 14 c have a smaller surface area, making it possible to achieve a further reduction in size and weight of the heat sink 14.

Third Embodiment

FIG. 4 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a third embodiment of the present invention. As shown in FIG. 4, the heat sink 24 has a base portion 4 a and four cooling fin blocks 24 b separated by slots 4 g, 4 h provided to run in directions parallel to and perpendicular to the moving direction of the car body 1, respectively. In this heat sink 24, the cooling fin blocks 24 b are structured such that the direction of grooves 24 f formed by flat-shaped cooling fins 24 c of the lower two cooling fin blocks 24 b of FIG. 3 and the direction of grooves 24 f formed by flat-shaped cooling fins 24 c of the upper cooling fin blocks 24 b are bilaterally symmetrical with respect to the slot 4 g.

While the width of the slot 4 g, or the distance between the cooling fin blocks 24 b in an up-down direction, is made larger than the width of the slot 4 h by a specific amount, the distances between these four cooling fin blocks 24 b in the up-down and left-right directions may be determined as appropriate depending on the size of the cooling fin blocks 24 b. Since the heat sink 24 has otherwise the same structure as the second embodiment shown in FIG. 3, corresponding elements are designated by the same reference symbols and a description of such elements is not given below. The heat sink 24 of this kind is manufactured by precision casting of an aluminum alloy, for example.

In this heat sink 24, traveling wind streams flow into the heat sink 24 from both upper and lower sides thereof as shown by arrows C in FIG. 4 and combine into a single airflow in the middle of the slot 4 g, and this combined airflow flows out from a right end of the heat sink 24 as shown by an arrow D. In this embodiment, the traveling wind streams which flow out from the upper cooling fin blocks 24 b and the traveling wind streams which flow out from the lower cooling fin blocks 24 b are combined into the single airflow and ejected. It is therefore possible to prevent the traveling wind streams which have flowed out from the upper cooling fin blocks 24 b from mixedly flowing into the lower cooling fin blocks 24 b, so that the cooling performance can be further improved. While the traveling wind flows in an opposite direction when the moving direction of the car body 1 is reversed, the heat sink 24 produces the same operational and working effects.

While the base portion 4 a is configured with a single plate in the second and third embodiments described above, the embodiments may be modified such that the base portion 4 a is divided into four parts depending on the number of the semiconductor devices 5 to be mounted and the cooling fin blocks 14 b, 24 b are provided separately on the four divided parts of the base portion.

Fourth Embodiment

FIG. 5 is a structural diagram showing a heat sink unit of an on-board cooling apparatus according to a fourth embodiment of the present invention. The heat sink unit shown in FIG. 5 is affixed to the side surface of the electrical equipment box 2 shown in FIG. 1 in the same way as the heat sink 4 of the first embodiment. As shown in FIG. 5, the heat sink unit 4 l is structured as if the heat sink 4 shown in FIG. 2 is provided with a louver 9. The louver 9 has rectangular, thin platelike slats 9 a which are disposed to project from ends of the individual flat-shaped cooling fins 4 c on lines extended therefrom at an upper peripheral part of the cooling fin block 4 b. All of the slats 9 a have the same dimensions.

Next, the working is described. Heat generated by the semiconductor devices 5 is conducted from the base portion 4 a of the heat sink 4 to the flat-shaped cooling fins 4 c and a heat exchange process is performed between the flat-shaped cooling fins 4 c and the traveling wind which has flowed into the grooves 4 f formed between the flat-shaped cooling fins 4 c. As a consequence, the semiconductor devices 5 are cooled. Due to the provision of the louver 9, it is possible to forcibly draw traveling wind streams which have passed through areas separated from the flat-shaped cooling fins 4 c into the grooves 4 f between the flat-shaped cooling fins 4 c. Therefore, the traveling wind can be introduced in larger quantities, thus achieving an increased cooling ability.

Fifth Embodiment

FIG. 6 is a structural diagram showing a heat sink unit of an on-board cooling apparatus according to a fifth embodiment of the present invention. As shown in FIG. 6, the heat sink unit 51 is structured as if the heat sink 4 shown in FIG. 2 is provided with a louver 19. The louver 19 has rectangular, thin platelike slats 19 a which are disposed to project from ends of the individual flat-shaped cooling fins 4 c on lines extended therefrom at an upper peripheral part of the cooling fin block 4 b. The length of projection of the slats 19 a provided on the upper end of the cooling fin block 4 b gradually increases downstream along the direction of the traveling wind, while the length of projection of the slats 19 a provided on the lower end of the cooling fin block 4 b gradually decreases downstream along the direction of the traveling wind.

While all of the slats 9 a are structured to project in the extending direction of the flat-shaped cooling fins 4 c by a specific length in the fourth embodiment shown in FIG. 5, the traveling wind streams are improved, producing a greater wind drawing effect, if the length of projection of the slats 9 a is gradually varied along the direction from the flat-shaped cooling fins 4 c located at the upstream side toward those located at the downstream side.

Sixth Embodiment

FIG. 7 is a structural diagram showing a heat sink of an on-board cooling apparatus according to a sixth embodiment of the present invention, FIG. 7( a) being a plan view of the heat sink and FIG. 7( b) being a sectional view showing a cross section taken along lines E-E as seen from a direction of arrows G. It is to be noted that semiconductor devices 5 are not shown in FIG. 7( b). As shown in FIG. 7, the heat sink 64 has a base portion 4 a and a cooling fin block 64 b which is formed integrally with the base portion 4 a. The cooling fin block 64 b has flat-shaped cooling fins 64 ca and flat-shaped cooling fins 64 cb of which height from the base portion 4 a is varied in a sinusoidal pattern along a longitudinal direction as seen in side view, wherein the flat-shaped cooling fins 64 ca and 64 cb are alternately arranged in a manner that crests and troughs of the flat-shaped cooling fins 64 cb and those of the flat-shaped cooling fins 64 ca are located opposite each other as depicted in FIG. 7( b). The flat-shaped cooling fins 64 ca and 64 cb together form grooves 64 f in between. Since the heat sink 64 has otherwise the same structure as the first embodiment shown in FIG. 2, corresponding elements are designated by the same reference symbols and a description of such elements is not given below.

Due to the provision of the flat-shaped cooling fins 64 ca, 64 cb having alternately varied shapes, it is possible to enhance the effect of drawing wind streams into the grooves 64 f so that a larger quantity of traveling wind passes through the grooves 64 f, thus producing an improved cooling effect.

Seventh Embodiment

FIG. 8 is a sectional side view of a heat sink of an on-board cooling apparatus according to a seventh embodiment of the present invention. It is to be noted that semiconductor devices 5 are not shown in FIG. 8. As shown in FIG. 8, the heat sink 74 has a base portion 4 a and a cooling fin block 74 b which is formed integrally with the base portion 4 a. The height of flat-shaped cooling fins 74 ca of the cooling fin block 74 b is varied in a sawtooth pattern along a longitudinal direction as seen in side view as depicted in FIG. 8. The height of flat-shaped cooling fins 74 cb is varied such that crests and valleys of the flat-shaped cooling fins 74 ca and those of the flat-shaped cooling fins 74 cb are located opposite each other. The cooling fin block 74 b is configured with these flat-shaped cooling fins 74 ca, 74 cb alternately arranged. The flat-shaped cooling fins 74 ca, 74 cb together form grooves 74 f in between. Since the heat sink 74 has otherwise the same structure as the first embodiment shown in FIG. 2, corresponding elements are designated by the same reference symbols and a description of such elements is not given below.

Due to the provision of the flat-shaped cooling fins 74 ca, 74 cb having alternately varied shapes, it is possible to enhance the effect of drawing wind streams into the grooves 74 f so that a larger quantity of traveling wind passes through the grooves 74 f, thus producing an improved cooling effect.

While the foregoing discussion of the individual embodiments has dealt with a case where the moving body is a body of a railroad car, the invention produces the same effect even when the moving body is a motor vehicle or a moving body of other kinds. 

1-5. (canceled)
 6. A moving body cooling apparatus to be installed on a moving body, said moving body cooling apparatus comprising: a heat-generating element mounting portion on which a heat-generating element to be cooled is mounted; and a cooling fin block formed integrally with said heat-generating element mounting portion, said cooling fin block having a plurality of cooling fins which form grooves extending in a direction inclined from a moving direction of the moving body; wherein said cooling fin block has a slot which divides said grooves at least in one of the directions parallel to and perpendicular to the moving direction of the moving body.
 7. The moving body cooling apparatus as recited in claim 6, wherein said cooling fin block has the slot running in the direction parallel to the moving direction of the moving body, and said plurality of cooling fins form said grooves in such a manner that said grooves are oppositely inclined with respect to the slot running in the direction parallel to the moving direction of the moving body.
 8. The moving body cooling apparatus as recited in claim 6, wherein a wind drawing member projecting from said cooling fins is provided in a direction extended from said grooves.
 9. The moving body cooling apparatus as recited in claim 6, wherein the height of said cooling fins from said heat-generating element mounting portion varies along a longitudinal direction of said grooves. 